The objective of this project is the development of a generator system to produce an ultrashort-lived radionuclide for clinical and investigative work in the cardiovascular system; namely, radionuclide angiocardiography. A disadvantage with presently available radionuclides is their relatively long physical half life which precludes the obtaining of more than one projection at a time, and to study the effects of exercise and pharmaceuticals in the hemodynamics. We are considering a radionuclide generator 1910s - 19lmIr (T-1/2 equals 4.9 sec; 0.129 MeV). Biological distribution, kinetic and toxicity studies will be carried out in various animal species. Animal studies using the gamma camera and the computer will be performed and computer programs for decay correction will be developed. This radionuclide will be used in the clinic for cardiovascular studies (i.e., detection, localization and quantitation of intracardiac shunts, ejection fraction and qualitative radionuclide angiocardiography). This ultrashort-lived radionuclide will allow: greater amounts of information because multiple projection of the flow through the central circulation will be possible; evaluation of the degree of shunting and other physiologic parameters during rest and exercise or under the effect of certain drugs; and significant reduction of the radiation dose to the patients compared to presently available radionuclides.